Add a workflow that simply:
1. checkout repo
2. write a file
3. create a PR

This is used to verify the permissions and validity of the github token we use to create PR.
context: https://chat.google.com/room/AAAAc_4rqiI/Ck593Sg7mvs

If we think the triggering condition is complicated, I can also change this workflow to be manual dispatch, to make it truly minimal.